Electric switch



Oct. 21, 1924. .1. 512,083

G. A. BURNHAM ELECTRIc swIT'cH' Filed Jupe 11. 1920 E?. QW \1 i-- l ik@ aff' Patented Oct. 21, 1924.

Y UNITED STATES PATENT OFFICE.

GEORGE A. BUIINHAM7 OF SAUGUS, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO CONDIT ELECTRICAL MANUFACTURING COMPANY, A CORPORATION OF MASSACHUSETTS.

ELECTRIC SWITCH.

Application filed June 11, 1820.

To all whom t may concern.'

Be it known that I, (',lnonon A. BURNHAM. a citizen of the United States, residing at Saugrus, in the county of Essex and State oi Massachusetts, have invented an Improvement in Electric Switches, oi? which the tollowingis a specification.

This invention relates to oil immersed switches adapted safely to carry and interrupt current of relatively high value.

The present type of oil switch comprises a switch trame and an oil receptacle den pending' therefrom adapted to contain oil i in which the switch members are immersed.

f A considerable space is provided under the switch frame over the oil which ervves as an expansion chamber for the switch; and said chamber is usually in communication with the atmosphere either through a relatively restricted or non-restricted vent passage.

Then the switch is in service, a mixture of oil vapor and air form in the expansion cl'iamher,` and under certain conditions which are of common occurrence in practice the mixture will be of explosive proportions. Under certain conditions of' circuit interruption. as when a heavy short occurs in the circuit controlled by the switch, the arc 'tormcd'between the switch members when the switch opens will extend above the sur- 'lacc otA the oil and contact with the explosive mixture and ignite it, or the gases formed upon circ-uit interruption will have such a` high temperature as to ignite the explosive mixture. In any event, the mixture is ignited and an explosion occurs and sutlicient pressure may be generated to wreck the switch; and burning oil may be scattered over the station.

It an explosive mixture is not present in the expansion chamber at the lirst circuit interruption, the oil vapor formed by the arc duringthe lirst circuit interruption will collect in the chamber and mix with the air in explosive proportions and the mixture will ignite upon the second circuit interruption. When a switch is operated several times in close succession, as may be the case with a remotely controlled switch arranged for automatic reclosing, and explosion may not occur upon the first operation but the chances are that an explosion will surely occur upon the succeeding operation.

Serial No. 388,324.

An object of this invention is the provision oi an electric switch having' means by which it is adapted to be ycomljiletely filled `with oil under the switch frame and in which there is no space :tor the collectionand retention et an explosive mixture of air andoil or other vapor whereby no explosion can oc cur.

A further object is to provide a switch adapted to be completely filled with oil having' a resiliently supported oil receptacle and preferably an outer spillreceptacle, as set forth in my cti-pending applications, Serial No. 309,853, tiled July 10, 1919; Serial No. 374,276, filed April 16, 1920; Serial No. 581,Li66, file May 14, 1920; and Serial No. 386,347, filed June 3, 192,0. y

At each operation of the kSwitch oil may be expelled from the oil receptacle and will be caught in the spill receptacle from which it' will be drawn off at suitable periods. As the loss of oil from the oil receptacle will result in the loweringr oitthe oil level therein and, eventually, in the formation of a clearance space beneath the switchr frame, in which a mixture of oil vapor and air may collect, a further object `of thev invention is to provide means automatically to maintain a proper level of oil therein or means to keep the switch full of oil.

A further object is generally to improve the construction and operation of an oil switch.

Certain features oi' this invention are also disclosed in my (to-pending ,applications Serial No. 300,557, tiled May 29, 1919 and Serial No. 390,850, iled June 22, 1920.

Fig. 1 is a side elevation, partly in section of a switch embodying my invention.

Fig. 2 is a transverse sectional elevation or" the switch of Fig. 1.

Fig. 3 is a sectional detail of the switch trame illustrating the switch rod 'bearing with its upper end elevated above the oil level.

Fig. a is a sectional detail illustrating the connection between the flexible oil supply pipe and the. oi] receptacle.v y

As here shown, the( switch embodying my invention includes the switch frame 10 having the extended arm 11 by which the switch is secured to a support. Stationary switch members l2 are carried by said frame and depend therebelow, and the movable switch member 18 supported, on the end of the switch rod 14: is also carried by said switch frame and is supported by the switch op erating mechanism 15.

Said switch frame 10 is formed with the peripheral flange or apron 16 which depends 'tor a substantial distance down the side wall :from the top of the oil receptacle 17 and incloses it but is peripherally spaced therefrom to provide a relatively narrow vent and. gas-cooling passage a between the Side wall of the oil receptacle and the iange for the venting of the switch. Said oil receptacle is contained within and supported by the outer or spill receptacle 18 and may be secured thereto by any suitable manner as spot-welding the bottoms of the two re ceptacles together. The side walls of said spill receptacle 18 are peripherally spaced from the side walls of the oil receptacle 17 whereby to form a relatively long; and narrow chamber in which vaporir/ied oil eX- pelled from the switch is adapted to be condensed and collected. The side walls ot said, spill receptacle preferably extend above the end of the apron 16 whereby substantially all of the oil and gas and vapor will be dif recited from the oil receptacle into the spill receptacle. The top of the spill receptacle is adapted to be relatively closely spaced trom the oil receptacle thereby to form a relatively narrow passage c which h owever` will be of ample area due to its large peripheral extent to provide a substantially unrestricti ed final vent passage from the switch; and, Vin connection with the shape of the chamber Z2, will prevent the maintenance et combustion of oil in the spill receptacle.

The spill receptacle rests upon ,Q rids 19 which extend laterally beyond the side walls ot the spill receptacle: and the extended portions thereot are provided with apertures therein. Rods 2O are arranged in said apertures and lixed to said .f rids and extend vertically upward alone' the opposite side walls of the spill receptacle and are slidably arranged in apertures in the lugs 21. carried by the switch frame. The upper ends ot said apertures are enlarged to torm the spring-receiving recesses 22. Compression springs 23 are arranged in said recesses and encircle said rods20. The upper ends of said rods are formed with the threaded portions 20ZL and nuts 241 are threaded thereon and engage the upper ends of said compression springs 23 whereby the oil receptacle will be movably disposed about the switch members and yieldingly supported from the switch frame.

The oil receptacle may be removed from the switch by removing said nuts 24 from said rods 20.

The construction of the oil and spill re ceptacles and the yielding; connection between lt and the switch Jframe is substantially as disclosed in my above named co pending` application Serial No. 309853, filed luly f1.07 19.19.

As above set forth an object of this invention is to provide an oil switch havingr means by which it is adapted to be completely lilled with oil whereby to eliminate any chamber ot appreciable dimensions in which air and oil vapor may collect in en plosive proportions and in dangerous amounts.

For this purpose the top portion 10a ot the switch frame which comprises a cover for vthe oil receptacle is adapted to extend tor a substantial distance into the oil re :eptacle 1'? below the top edge thereof7 and is formed with the upwardly extended portion 1()b which in conjunction with the apron 16 forms a peripheral groove d in which the upper portion of the oil receptacle is received. Said portion 10a of the switch trame is spaced a substantial distance from the inner tace ot the oil receptacle whereby to provide a substantially unrestricted commiinicatinej passage for gas and vapor to the outer vent passage a. Under normal conditions the oil receptacle is adapted to be completely filled with oil to its top or at least above the lower portion 10a of the cover. Said portion 10FL is inclined from its center portion upwardly toward its sides whereby to guide gas or vapo-r generated in the switch into the periheral `groove l and prevent it from bei ne" entrapped within the switch.

lfilhile for certain purposes the top of the il` receptacle may be in more or less substantial contact with the switch frame at the bottom of the groove d, in which position the switch will be what is termed noir vented, yet there will be a suiiicient amount olf' clearance between the top ot the receptacle and the switch trame to permit the switch to breathe. lt prettier, however`v to maintain a clearance between the top of the switch and the switch -frame at least as ample as the clearance between the side walls ot the receptacle and the apron 1G whereby there will be a substantially unrestricted vent passage from the surface of the oil in the switch to the atmosphere. For this purpose, the rods 20 are provided with the sleeves 25 which are vtixed. thereon in such a position that they will engage the lower ends of the lugs 21 to restrict the further upward movement of the receptacle under action of the springs 23 and maintain the top of the oil receptacle 17 a suitable predetermined distance away 'from the switch frame.

The switch members 12 are arranged in bosses 10'C of the switch trame. Said bosses are adapted to extend above the top ot the oil in the oil receptacle whereby under normal conditions no oil will flow from the rean explosive mixture may collect.

ceptatle between said switch members and `the switch frame at this point. The switch frame is also provided with the boss l()l1 through which the switch rod la is slidably extended and said boss also is adapted to extend above the level of the oil in the oil receptacle.

As above set forth oil is adapted to be maintained in the oil receptacle to and preferably above the portion 10a of the cover whereby the switch will be completely lilled with oil and no space will be provided in which an explosive mixture can collect; and preferably the oil level is adapted to extend substantially to the top of the oil receptacle or at least more or less completely till the groove l in the switch rame.

hile this arrangement will initially provide a completely filled oil receptacle, yet under conditions of. severe circuit interruption oil will be expelled from the switch so Vthat at some subsequent period the oil level may have sunk to such a point that an appreciable space may exist above the suriace 1ot the oil beneath the cover in which In view of this, I provide means automatically to admit oil into the switch when the oil level therein becomes dangerously low thereby to maintain the oil level and to restore it to its proper level after oil has been yexpelled from the switch.

The oil receptacle is arranged for communication with an oil supply such as an elevated tank or other source, not shown, Adisposed at some convenient point in the station.

A float valve is provided which is governed by the level of oil within the switch automatically vto open or close as the oil level within the switch recedes from or approaches the predetermined point. Then oil is expelled from the switch and the oil level is consequently lowered lthe loat valve will open to permit oil to flow 'trom the oil source into the oil receptacle. When the oil level is restored the float valve will automatically close. The float valve may be arranged at any convenient position but I prefer to support it from the switch frame.

As here shown, the float valve is enclosed in the float chamber 26 which is secured to the arm 1l of the switch frame. The float valve 27 arranged within said chamber is governedA by the float 28 to control admission of oil therein through the pipe 29 which is adapted to extend and be in communication with the source ot' oil supply. The float chamber is so supported that the level of rthe oil therein will correspond with the level of oil in the oil receptacle of the switch and when the oil level in the oil receptacle is at the proper oint the oil level in the float chamber wil be such as oil therefrom and a i'iexible pipe 3l extends 'from said valve to the oil receptacle. Connection is made with the oil receptacle 17 of the switch through the ,pipe or nipple 32 which extends through aligned openings in corresponding side walls of the outer and inner receptacles near the bottoms thereoit and is secured thereto in oil tight relation therewith by the locli nuts 33 or equivalent. Said nipple 32 extends beyond said spill receptacle 18 and a check valve 33 is arranged thereon whereby to prevent bach flow of oil from the switch when a pressure is developed therein. Said flexible pipe 3l; is connected with said check valve 33 bv the coupling 34 by which it may be detached from the oil receptacle when it is desired to remove the receptacle.

The valve is adapted to be closed when. it is desired toremove the oil receptacle whereby to prevent the flow of oil from the pipe 29. The flexible connection with the oil receptacle formed by the pipe 3l admits of the yielding of the oil receptacle or its movementl downward under conditions olf circuit interruption.

An oil gauge 35 is secured in the side wall of the spill receptacle 18 near the bottom thereof to indicate the height of oil therein and the pet-cock 36 admits of excess oil being drawn olf.

It is obvious thatr the construction above set forth can be variously modified without departing from the spirit of the invention.

I claim:

l. An electric switch adapted to be completely :filled with oil having a substantially unrestricted vent passage extending from the surface ot' the oil in the switch downwardly below the surface oit the oi! to the atmosphere, and means to maintain thc switch completely [illed with oil.

2. An electric switch comprising an oil receptacle and a switch frame coi'rnorising a cover for said receptacle, said switch adapted to be completely filled with oil to its cover and having a substantially unrestricted vent passage extending trom the surface of the cil downwardly below the surface of the oil to the atmosphere, and means to maintain the switch completely filled with oil.

3. An electric switch comprising alfixed switch frame comprising a cover for tbc oil receptacle, and an oil receptacle yieldingly supported beneath said frame,y said switch adapted to be completely filled 'with oil to said cover, and said cover and receptacle cooperating to provide a communicating passage from the surface of the oil at the periphery of said oil receptacle to the atmospliere7 and means to maintain the switch completely filled with oil.

4. An electric switch comlirising a fixed switch Yframe con'iprising a cover for the oil receptacle, and an oil receptacle removably supported beneath said frame, said switch adapted to be completely filled with oil to said covery and said cover and receptacle coci'ierating to provide a communicating passage from the surface of the oil at the periphery of said oil receptacle to the atmosphere and means to maintain the switch completely filled with oil.

An electric switch con'xprisinn a fixed switch iframe coii'iprisingg' a cover for the oil receptacle7 and an oil receptacle removably and yieldingly supported beneath said frame, said switch adapted to be completely filled with oil to said cover, and said cover and receptacle cooperating to provide a communicating passage from the surface of the oil at the periphery of said oil. receptacle to the atmosphere and means to maintain the switch completely filled with oil,

(i. An electric switch comprising' a fixed switch frame comprising: a cover for the oil receptacle and an oil receptacle yieldingly supported from said fixed frame, said switch adapted to be filled with oil to its cover and having' a substantially unrestricted vent passage extending` from the surface of the oil downwardly below the surface of the oil to the atmosphere and means to maintain the switch completely filled with oil.

7. An electric switch comprising a fixed switch frame comprising a cover for the oil receptacle and an oil receptacle removably and yieldingly supported from said fixed framei said switch adapted to be filled with oil to its cover and having a substantially unrestricted vcnt passage extending` `from the surface of the oil downwardly below the surface of the oil to the atmosphere and means to maintain the switch con'ipletely filled with oil.

8. An electric switch con'iprisingf a :fixed switch frame comprisingn a, cover for the oil receptacle, and an oil receptacle yielding'lv supported from said fixed frame, said switch adapted to be completely filled with oil to its cover and said cover and receptacle cooperating to provide a substantially unrestricted peripheral vent and gas cooling passage extending' from the surface ot the oil at the periphery of the oil receptacle downwardly below the surface of the oil to the atmosphere and means to maintain the switch completely filled with oil.

9. An electric switch comprising a fixed switch frame comprising cover for the oil receptacle, and an oil receptacle removably and yieldingly supported from said fixed frame, said switch adapted to be completely filled with oil to its cover, and Said cover relapse and reci-fptacle cooperating` to provide a sub stantially unrestricted peripheral. vent and gras cooling` passage -xtending from the surface of the oil at the periphery of the oil receptacle downwardly along the outer surface of the oil receptacle to the atmosphere and means to maintain the switch completely filled with oil.

l0. in electric switch comprising` a fixed switch iframe comprising a cover for the oil receptacle, and an oil receptacle yieldingly supported relative to said frame., said switch adapted to be completely filled with oil to the cover and having` a substantially unrestricted vent passageA extending` from the surface of the oil to the atmosphere and means to maintain the switch completely .filled with oil.

il. An electric switch comprising a fixed switch frame comprisinga a cover for the oil. receptacle and -an oil receptacle removably and yieldingly supported relative to said fixed frame, said switch adapted to be completely filled with oil to its cover, and said cover and receptacle cooperating to provide a substantially unrestricted vent and gascoolingj passage extending from the surface of the oil at the'periphery of the oil receptacle downwardly along the outer surface of the oil receptacle below the surface of the oil to the atmosphere and means to maintain the switch completely filled with oil.

12. An electric switch comprising a relatively yielding' switch frame comprising a cover for the oil receptacle, said switch arranged to be completely filled with oil to its cover, said switch frame and said oil receptacle cooperating: to provide a peripheral vent and gas-cooling passage for the switch over the top of the oil receptacle, and a spill receptacle enclosing said oil receptacle extended above the end of the vent passage to collect oil expelled vfrom the switch and means to maintain the switch completely filled with oil.

13. An electric switch comprising a relatively movable switch frame comprising a cover for the oil receptacle and an oil receptacle, said switch adapted to be com pletely filled with oil to the cover, said cover having a peripheral apron enclosing the top portion of and depending` down and peripherally spaced from the side walls of the oil receptacle to provide a vent passage for the switch between it and the oil receptacle and a spill receptacle disposed beneath the lower` end of said passage to collect oil expelled from the switch and means to maintain the switch completely filled with oil.

14. An electric switch comprising an oil receptacle, a switch frame comprising a cover for said receptacle extended into said receptacle and having a. peripheral groove in which the top portion of said receptacle is received and a peripheral apron depending over and peripherally spaced from the outer face of the side walls of said receptacle to provide a vent passage for the switch between it and the receptacle.

15. An electric switch comprising an oil receptacle, a switch frame comprising a coverfor said receptacle extended into said receptacle and having a peripheral groove in which the top portion of said receptacle is received and a peripheral apron depending over and peripherally spaced from the outer face of the side walls of said receptacle to provide a vent passage for the switch between it and the receptacle, and a spill receptacle containing said oil receptacle" jarranged beneath said apron to catch oil ex pelled from the switch.

16. An electric switch having a receptacle freely vented to the atmosphere and adapted to contain oil in which the switch members are immersed and means independent of the vent to introduce oil into the receptacle to maintain a predetermined level of oil therein. l

17. An electric switch having an oil receptacle vented to the atmosphere, means to catch oil expelled from said receptacle through the vent, and means independent of the vent to admit oil in said receptacle and restore the oil level therein.

18. An electric switchhaving the combination of a resiliently supported oil receptacle, and a flexible fluid conductor extended from. a fixed support to and in connnunication with said oil receptacle.

19. An electric switch having the conibination ol a resiliently supported oil re ceptacle, and a flexible fluid conductor extended lrom a fixed support to said oil receptacle and means detachably connecting it with said receptacle.

20. An electric switch having the combination of a llxed switch frame, an oil receptacle yieldingly depending from said traine a float chamber adapted for connection with a source ol oil supply carried by said frame, and a flexible oil'conductor extended between and in communication with said float chamber and oil receptacle and detachably connected with said oil receptacle.

21. An electric switch having the combination of a 'fixed switch traine, an oil receptacle yieldingly depending from said frame. a float chamber adapted for connection with a source of oil supply carried by said trame?, a llexible oil conductor extended between and in communication with said float chamber and oil receptacle detachably connected with said oil receptacle and a valve at said float chamber controlling the admission of oil into said conductor.

22. An electric switch having an inner' receptacle adapted to contain oil in which the switch members are immersed. an outer spill receptacle containing said oil recep tacle, and a pipe extended through the side walls of said outer and inner receptacles and secured therein against oil leakage and in communication with said inner receptacle having means at its outer end for connection with an oil conductor.

23. An oil immersed electric switch having relatively movable switch-members, an enclosing casing adapted to contain oil in` which said switch-members are immersed and in which the circuit-interrupting arc is formed, said casing having a free gas vent to the atmosphere and fluid means to maintain the casing free from any substantial amount of a gaseous explosive mixture.

24. An oil immersed electric switch having relatively movable switclrmembers, an enclosing casing adapted to contain oil in which said switch-members are immersed, and in which the circuit-interrupting arc is formed, said casing having a free gas vent to the atmosphere, and means to inaintain the casing free from any substantial amount of a gaseous explosive mixture, said means including means to maintain the ca sing substantially completely illled with oil and exclude any substantial gas volume above the surface of the oil within the casing.

In testimony whereof, I have signed my name to this speciication.l

GEORGE A. BURNHAM. 

